The present invention relates to protective yarns. More particularly, the present invention relates to a protective yarn having a fiberglass fiber core and one or more cover members of fibers that are of dissimilar materials from the core fibers.
Protective clothing has existed for hundreds of years. Among the first type of protective clothing was armor worn by knights. Of course, these heavy and inflexible metal sheets limited a knight""s movement and visibility. While providing excellent protection against blade injuries, plate armor limited the manual dexterity of the wearer. Later, armorers developed chain mail, and while permitting some manual dexterity on the part of the wearer, their mail was heavy and quickly fatigued the wearer.
Until recently, meat cutting plants employed chain mail type gloves to prevent accidental cuts to a meat cutters"" hands. Like their medieval counterparts, the choir mail worn by meat cutters quickly fatigued the user""s hands.
More recently, users needing protection against cuts and also requiring a high level of dexterity have turned to gloves knitted from engineered yarns. While dramatically increasing the flexibility and manual dexterity, gloves engineered using aramid fibers such as xe2x80x9cKevlar(copyright)xe2x80x9d and gloves engineered using ultrahigh molecular weight polyolefin fiber such as ultrahigh molecular weight polyethylene or polypropylene extended chain polyethylenes are extremely costly. Commercial examples of gloves using these engineered yarns include Spectra(copyright) 900 and Spectra(copyright) 1000, sold by AlliedSignal, Inc and Kevlar(copyright), sold by the Du Pont Company of Wilmington, Del. Garments knitted with yarns such as Spectrao have problems with yarn shrinkage.
A need, therefore, exists for an engineered protective yarn which provides cut protection and freedom of movement at a lower cost. A need also exists for an engineered protective yarn which resists the effects of high temperatures such as shrinkage.
Numerous attempts have been made to employ fiberglass fiber in protective yarns which are then knitted into protective gloves. However, a new problem has been created by adding fiberglass fiber to yarn. Fiberglass fiber is brittle and small glass fragments are likely to separate from the glass fibers and irritate the skin of the user. Naturally, glove irritation reduces the likelihood that a user will wear their protective garments. Attempts have been made to coat fiberglass fiber in order to prevent skin irritating fragments from detaching from the main fiber strand. However, these coating attempts have proven to be less than completely successful.
Applicants are aware of the following relevant U.S. Patents.
U.S. Pat. No. 4,384,449 shows protective gloves and the like and a yarn comprising a core of a flexible wire alongside an aramid fiber strand or strands and a covering of aramid fiber such as that manufactured and sold under the trademark xe2x80x98Kevlarxe2x80x99 by the DuPont Company of Wilmington, Del. in which the aramid fiber is either spun or filament. Two aramid fiber strands, either spun or filament, are wrapped around the core with one strand wrapped in a clockwise direction and the other strand wrapped in a counter-clockwise direction with the opposite spiral wrapping of the strands serving to secure the strands in position on the core without any other securing means. The yarn having a flexible core with aramid fiber strands wrapped thereon is used to make protective gloves on conventional glove knitting or weaving machinery and is capable of movement in relation to needle eyes and the like without jamming in the same manner as various natural and synthetic fiber yarns. The yarn having a flexible core with aramid fiber strands wrapped thereon is also used in making various other products normally made of conventional fiber yarn.
U.S. Pat. No. 4,651,514 shows an electrically non-conductive, cut and abrasion resistant yarn for use in the manufacture of protective coverings including a core of monofilament nylon having a diameter in the range of about 0.004 to 0.020 inches, a first wrap on the core of at least one strand of aramid fiber having a cotton count size in the range of about 1/1 to 30/1 and a second wrap on the core of texturized nylon of two to eight ply construction. Each ply is made up of 24 to 44 nylon filaments with each filament being about 50-90 denier.
U.S. Pat. No. 4,777,789 shows an improved yarn, fabric and protective garment made from such yarn where the yarn, fabric and garment exhibit increased cut resistance. The yarn includes a core made of fiber and a covering wrapped around the core, the covering includes at least one strand of wire wrapped around the core.
U.S. Pat. No. 4,818,587 shows nonwoven fabrics contain at least 30% by weight of heat-adhesive composite fibers consisting of core portion and sheath portion, said core portion being of the side-by-side type composite structure comprising two core components of different polypropylene base polymers in a composite ratio of 1:2 to 2:1, one of said core components having a Q value, expressed in terms of the weight-average molecular weight/the number-average molecular weight, equal to or higher than 6 and the other having a Q value equal to or lower than 5, and said sheath portion meeting at least the requirement that it should comprise a sheath component of a polyethylene base polymer having a melting point lower by at least 20xc2x0 C. than the lower one of the melting points of said two core components. The nonwoven fabrics are bulky and soft due to the crimps of the heat-adhesive composite fibers esultant form the core portion and are stabilized by the inter-fiber bonds of the sheath portion.
U.S. Pat. No. 4,838,017 shows an improved yarn, fabric and protective garment made from such yarn where the yarn, fabric and garment exhibit increased cut resistance. The yarn includes a core made of fiber and a covering wrapped around the core, the covering includes at least one strand of wire wrapped around the core.
U.S. Pat. No. 4,886,691 shows a cut resistant article comprising a cut resistant jacket surrounding a less cut resistant member. The jacket comprises a fabric of yarn and the yarn consists essentially of a high strength, longitudinal strand having a tensile strength of at least 1 GPa. The strand is wrapped with another fiber or the same fiber.
U.S. Pat. No. 4,936,085 shows an improved yarn, fabric and protective garment made from such yarn, where the yarn, fabric and garment exhibit increased cut resistance, flexibility, pliability and softness. The yarn is non-metallic and includes a core made of fiber and a covering wrapped around the core. At least one of the strands is fiberglass, the non-fiberglass strands are preferably nylon or polyester.
U.S. Pat. No. 5,010,723 shows a yarn produced from two or more twisted cellulosic fibers, such as cotton or cotton rayon fibers, the plies being helically wound around a thermoplastic filament core which is subsequently melted to bind the inner portions of the yarn together so that it does not untwist or shed lint readily. The yarn is employed in a dust mop or floor mat for a shampoo bonnet for stain resistant treated carpet.
U.S. Pat. No. 5,119,512 shows a cut resistant article comprising a cut resistant jacket surrounding a less cut resistant member. The jacket comprises a fabric of yarn and the yarn consists essentially of a high strength, longitudinal strand having a tensile strength of at least 1 GPa. The strand is wrapped with another fiber or the same fiber. In another embodiment, the invention is a highly cut resistant yarn of at least two nonmetallic fibers. One fiber is inherently cut resistant like high strength polyethylene, polypropylene or aramids. The other fiber in the yarn has a high level of hardness.
U.S. Pat. No. 5,177,948 shows an improved non-metallic yarn, fabric and protective garment made from such yarn, where the yarn, fabric and garment exhibit increased cut resistance, flexibility, pliability and softness. The yarn is non-metallic and includes a core made of fiber and a covering wrapped around the core. At least one of the strands of the core is fiberglass, the non-fiberglass strands are preferably nylon, extended chain polyethylene, aramid or polyester.
In a preferred embodiment of the present invention, a protective yarn has a single fiberglass core fiber and one or more cover members. The cover members are selected from the group consisting of aramid fiber, ultrahigh molecular weight polyolefin fiber, polyester, nylon and polyacrylic fibers. The cover members are wrapped, wound or twisted around the core in a manner which permits successive layers to be wrapped, wound or twisted around the core in an direction opposite that of the cover member immediately below.
By using only one fiberglass core instead of multiple non-glass fiber cores, the present invention provides cut resistance cut resistant fibers such as Spectral and Kevlarm at a significantly lower cost. Substituting a lower strength hard and brittle fiber material such as fiberglass to the core of the yarn adds a significant level of cut resistance at a fraction of the cost. The addition of new yarn components has substantially reduced a user""s manual dexterity problems and increased the protection offered for cuts.
The present invention overcomes the limitations of existing protective yarns by using a single longitudinal core fiber that is a hard and brittle material. Typically, the core material is a strand of fiberglass. In order to minimize the amount of fiberglass fragments that break free from the fiberglass strand and irritate the skin of the person coming in contact with the fiberglass fragments, a series of covering wraps are employed. These covering wraps may also be a highly cut resistant material in and of themselves. In addition, the outer cover wrap may be a fiber that is smooth to the touch such as polyester or nylon. However, in order to maximize cut resistance, the covering wraps may be selected from the group consisting of polyolefins such as Spectram or aramids such as Kevlar(copyright).
Preferably, the cover members are wrapped, wound or twisted around the core in a manner which permits successive layers to be wrapped, wound or twisted around the core in an opposite direction from the cover element immediately below.
The resulting protective yarns are then suitable for knitting into protective gloves and other protective garments. These yarns offer an inexpensive alternative to existing protective yarns while providing substantial cut protection without irritating a user""s skin.
An object of the present invention is to provide a protective yarn.
Another objective of the present invention is to provide a yarn with a sufficiently low composite denier such that the composite yarn is knittable into a protective glove or other protective apparel.
Another objection of the present invention is to provide a protective yarn that can be knitted into a glove which does not irritate the wearer""s skin, thereby increasing the likelihood that a person will continuously wear the gloves.
Another object of the invention is to provide a protective yarn that can be knitted into a glove which is flexible and which does not unacceptably diminish the manual dexterity of the wearer.
Another objective of the present invention is to provide a protective yarn that can maintain its size when it is exposed to the extremely high temperatures employed in washing protective garments and gloves in order to kill bacteria.
Another objective of the present invention is to minimize the undesirable shrinkage of composite yarns having SpectraO fiber or other similar fiber when the composite yarn is subjected to the cleaning process.
Another objective of the present invention is to provide a yarn having fewer defects for efficient knitting of protective garments and gloves with superior characteristics.
From the foregoing, it is readily apparent that we have invented an improved protective yarn. The improved protective yarn is a single longitudinal fiberglass fiber core wraped with cover layers composed of fibers selected from the group consisting of polyolefins such as Spectra(copyright) or aramids such as Kevlar(copyright). Winding the cover layers on the fiberglass core so that an adjacent cover layer is wound in a direction opposite to the layer immediately beneath it gives the protective yarn the desired characteristics at a much lower cost than existing yarns. The invented protective yarn is flexible enough that it can be knitted into a protective fabric or garment on conventional knitting or weaving machines and yet is strong enough to offer substantial cut resistance. Finally, the invented protective yarn resists shrinkage which results from exposure to extremely high temperatures during the washing process.